Water leakage through man made metal shingles has been a problem for many years. The problem is particularly troublesome for shingles which are adapted to be installed from top down beginning at a roof ridge. The problem is most severe for roofs having relatively low slopes of 4-12 (4" in 12") or less from which water does not drain quickly. Water penetration through installed metal shingles can occur by capillary action which is difficult to prevent.
U.S. Pat. No. 1,519,350 discloses a sheet metal shingle which is adapted to be installed beginning at a roof ridge and proceeding downwardly. The shingle has a male portion along its top edge, a female portion adjacent its bottom edge, and an attachment or nailing flange below the female portion. The shingle also has open folded flanges on opposite sides which are interengaged when the shingle is installed on a roof.
U.S. Pat. No. 4,759,165 discloses a roofing panel having side edges formed by a curved transition portion and a return bend flange. A bead of resilient sealant material is adhered within the curved transition portion to provide a seal with respect to the adjacent panel. U.S. Pat. No. 3,394,515 shows a deformable gasket in a channel along a side edge of a roofing panel. The gasket forms a seal with an interlocking edge of an adjacent panel. Other uses of beads of sealant materials in roofing panels are disclosed in U.S. Pat. Nos. 4,316,351; 4,184,301 and 4,223,503.
There is a need for a sheet metal shingle that is adapted to be installed on a roof beginning at a roof ridge and proceeding downwardly, and which resists water penetration through the shingles to the underlayment. Such a shingle is especially desired for application on roofs with relatively low slopes.